# TEM TE and TM Modes for Waveguides ?

In summary, the conversation is about someone seeking help with understanding TEM, TE, and TM modes for waveguides and finding equations for planar and optical fiber waveguides. They found a link for rectangular waveguides but are looking for one for planar waveguides. The other person suggests using the same method but removing the component for side walls if the waveguide has two infinite PEC sheets a certain distance apart. They also mention that the wave is unconstrained in the x direction.
hello ;
I need some help.I reading about TEM TE and TM Modes for Waveguides. actually I need some equations for Planar wave guide and optical fiber wave guide. I did google search. I don't understand how to write equation step by step for planar wave guide
but that's for rectangular wave guide and I am looking for planar waveguide

When you say planar waveguide, are you saying 2 (infinite) PEC sheets a certain distance apart? If that is the case, your development in the link you sent should work in theory, just take away the component relating to the side walls.
Say you want TM to z, so all wave components are in the x, and y directions and your waveguide is at y=0 and y=a.
Your wave is unconstrained in the x direction, so you will get modes in y that will still use ##\frac {m \pi}{a}##.

## 1. What are TEM, TE, and TM modes for waveguides?

TEM, TE, and TM modes are different types of electromagnetic wave propagation in a waveguide. TEM stands for Transverse Electromagnetic mode, TE stands for Transverse Electric mode, and TM stands for Transverse Magnetic mode.

## 2. What are the differences between TEM, TE, and TM modes?

The main difference between TEM, TE, and TM modes is the orientation of the electric and magnetic fields with respect to the direction of propagation. In TEM mode, both the electric and magnetic fields are perpendicular to the direction of propagation. In TE mode, the electric field is perpendicular to the direction of propagation while the magnetic field is parallel. In TM mode, the magnetic field is perpendicular to the direction of propagation while the electric field is parallel.

## 3. How are TEM, TE, and TM modes excited in a waveguide?

TEM mode can only be excited in a waveguide with two conductive walls, such as a coaxial cable. TE and TM modes can be excited in a waveguide with one conductive wall, such as a rectangular waveguide, by using an external source or by creating a discontinuity in the waveguide.

## 4. What are the applications of TEM, TE, and TM modes in waveguides?

TEM mode is commonly used in RF and microwave transmission lines, while TE and TM modes are used in waveguides for guiding electromagnetic waves at higher frequencies. They are widely used in various applications such as radar systems, satellite communication, and waveguide filters.

## 5. How do I determine the cutoff frequency for TEM, TE, and TM modes in a waveguide?

The cutoff frequency for TEM mode can be easily determined by the dimensions of the waveguide. For TE and TM modes, the cutoff frequency is determined by the dimensions of the waveguide and the mode number. There are various online calculators and software tools available to calculate the cutoff frequency for different waveguide configurations.

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